请你用Java写一个2048小游戏

好的，以下是一个简单的Java实现2048小游戏的代码：

import java.util.Scanner;

public class Game2048 {
    private static int[][] board = new int[4][4];
    private static boolean isGameOver = false;

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        initBoard();
        printBoard();
        while (!isGameOver) {
            System.out.print("请输入方向（w:上, s:下, a:左, d:右）：");
            String direction = scanner.nextLine();
            move(direction);
            if (!isGameOver) {
                generateNumber();
                printBoard();
            }
        }
        System.out.println("游戏结束！");
    }

    private static void initBoard() {
        for (int i = 0; i < board.length; i++) {
            for (int j = 0; j < board[i].length; j++) {
                board[i][j] = 0;
            }
        }
        generateNumber();
        generateNumber();
    }

    private static void generateNumber() {
        int x, y;
        do {
            x = (int) (Math.random() * 4);
            y = (int) (Math.random() * 4);
        } while (board[x][y] != 0);
        board[x][y] = Math.random() < 0.9 ? 2 : 4;
    }

    private static void printBoard() {
        System.out.println("┌───┬───┬───┬───┐");
        for (int i = 0; i < board.length; i++) {
            for (int j = 0; j < board[i].length; j++) {
                System.out.printf("│%4d", board[i][j]);
            }
            System.out.println("│\n├───┼───┼───┼───┤");
        }
        System.out.println("└───┴───┴───┴───┘");
    }

    private static void move(String direction) {
        boolean isMoved = false;
        switch (direction) {
            case "w": // 上移
                for (int j = 0; j < board[0].length; j++) {
                    for (int i = 1; i < board.length; i++) {
                        if (board[i][j] != 0) {
                            int k = i;
                            while (k > 0 && board[k - 1][j] == 0) {
                                board[k - 1][j] = board[k][j];
                                board[k][j] = 0;
                                k--;
                                isMoved = true;
                            }
                            if (k > 0 && board[k - 1][j] == board[k][j]) {
                                board[k - 1][j] *= 2;
                                board[k][j] = 0;
                                isMoved = true;
                            }
                        }
                    }
                }
                break;
            case "s": // 下移
                for (int j = 0; j < board[0].length; j++) {
                    for (int i = board.length - 2; i >= 0; i--) {
                        if (board[i][j] != 0) {
                            int k = i;
                            while (k < board.length - 1 && board[k + 1][j] == 0) {
                                board[k + 1][j] = board[k][j];
                                board[k][j] = 0;
                                k++;
                                isMoved = true;
                            }
                            if (k < board.length - 1 && board[k + 1][j] == board[k][j]) {
                                board[k + 1][j] *= 2;
                                board[k][j] = 0;
                                isMoved = true;
                            }
                        }
                    }
                }
                break;
            case "a": // 左移
                for (int i = 0; i < board.length; i++) {
                    for (int j = 1; j < board[i].length; j++) {
                        if (board[i][j] != 0) {
                            int k = j;
                            while (k > 0 && board[i][k - 1] == 0) {
                                board[i][k - 1] = board[i][k];
                                board[i][k] = 0;
                                k--;
                                isMoved = true;
                            }
                            if (k > 0 && board[i][k - 1] == board[i][k]) {
                                board[i][k - 1] *= 2;
                                board[i][k] = 0;
                                isMoved = true;
                            }
                        }
                    }
                }
                break;
            case "d": // 右移
                for (int i = 0; i < board.length; i++) {
                    for (int j = board[i].length - 2; j >= 0; j--) {
                        if (board[i][j] != 0) {
                            int k = j;
                            while (k < board[i].length - 1 && board[i][k + 1] == 0) {
                                board[i][k + 1] = board[i][k];
                                board[i][k] = 0;
                                k++;
                                isMoved = true;
                            }
                            if (k < board[i].length - 1 && board[i][k + 1] == board[i][k]) {
                                board[i][k + 1] *= 2;
                                board[i][k] = 0;
                                isMoved = true;
                            }
                        }
                    }
                }
                break;
            default:
                System.out.println("无效的方向！");
        }
        if (isMoved) {
            checkGameOver();
        }
    }

    private static void checkGameOver() {
        for (int i = 0; i < board.length; i++) {
            for (int j = 0; j < board[i].length; j++) {
                if (board[i][j] == 0) {
                    return;
                }
                if (i < board.length - 1 && board[i][j] == board[i + 1][j]) {
                    return;
                }
                if (j < board[i].length - 1 && board[i][j] == board[i][j + 1]) {
                    return;
                }
            }
        }
        isGameOver = true;
    }
}

玩家每次输入方向键后，程序会将数字方块向该方向移动，并在空白处随机生成一个新的数字方块（2或4）。如果相邻的两个数字方块的数字相同，则它们会合并成一个新的数字方块，数字为原来两个数字的和。当所有方块都被填满，且相邻的数字方块没有相同的数字时，游戏结束。